PHOTO: AFP
Turkey in October 2013 opened the Marmaray rail tunnel underneath the iconic waterway, the first link beneath the waters that divide Europe and Asia.
But from Tuesday it will be possible for the first time in history to drive underneath the Bosphorus due to a project aimed at relieving congestion in the traffic-clogged Turkish mega city.
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Erdogan is expected to drive himself to make the first journey from Europe to Asia in the Avrasya (Eurasia) Tunnel along with Prime Minister Binali Yildirim after the opening at 1100 GMT.
The tunnel required an investment of $1.2 billion (1.15 billion euros), including loans of $960 million, and will reduce driving time for the route from up to 2 hours to 15 minutes.
It was built by a consortium consisting of private Turkish construction company Yapi Merkezi and South Korea's SK Group.
The project comprises a 5.4 kilometer (3.5 mile) tunnel, with the portion beneath the Bosphorus 3.4 kilometers long.
The two-storey tunnel was built with a special tunnel boring machine which had a daily progress speed of 8-10 meters (26-32 feet) on average.
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According to the designers, the earth dug in the project would be enough to fill 788 Olympic pools, the cement poured would fill 18 stadiums, while the iron used could build 10 Eiffel Towers.
With Istanbul lying on an active seismic zone, the tunnel has been designed to withstand a 7.5 magnitude earthquake.
It would be undamaged even if Istanbul saw a once-in-500-year earthquake. And the tunnel could resume operation "with slight maintenance works" in the event of a once-in-2,500-year earthquake.
Turkish Transport Minister Ahmet Arslan told AFP ahead of the opening that it had been a "huge challenge" to build the tunnel at a depth of 106 meters under the seabed.
He revealed the authorities now planned to build a third tunnel under the Bosphorus that would have three storeys and carry both cars and trains.
"I think the Avrasya tunnel will hugely ease the lives of the residents of Istanbul," Arslan told AFP. "But we are not just going to stop there."
Erdogan has said he is aiming to build a "new Turkey" with transformed infrastructure in time for the 100th anniversary in 2023 of the foundation of the modern state by Mustafa Kemal Ataturk.
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Other schemes, which Erdogan boasts are his "crazy projects", include a gigantic third airport for Istanbul, the first ever bridge across the Dardanelles straits and even a Suez-style shipping canal for Istanbul.
Erdogan has vowed that his ambitions will not be derailed by the failed July 15 coup and the swathe of terror attacks Turkey has suffered this year.
Just one month after the attempted coup, Erdogan opened the third bridge across the Bosphorus named after the medieval sultan Selim the Grim.
"These kinds of events will not deviate us from our path," Erdogan said at the weekend after 14 soldiers were killed in an attack blamed on Kurdish militants.
The tunnel opening also comes one day after a Turkish policeman crying "Aleppo" and "Allahu Akbar" shot dead Russia's ambassador to Turkey at an exhibition centre in Ankara.
Suggestions for the naming of the new tunnel included Ataturk himself and the late-period Ottoman Sultan Abdulhamid II, an arch-conservative whose reputation has undergone a major revival in Turkey in recent years.
But the authorities have settled on the far less politically-loaded Avrasya Tunnel, despite a high-profile campaign by officials for the public to submit names.
"In public consultations, many names came out but Avrasya really was the most ideal," said Arslan.
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